Refreshing particular part of Page Without Refreshing Whole Page

Place your content inside Ajax UpdatePanel. And use Ajax timer to refresh the same content for regular interval of time.

Ex:

<asp:ScriptManager runat="server" ID="ScriptManager1" />
<asp:Timer ID="Timer1" runat="server" Interval="1000" OnTick="Timer1_Tick">
</asp:Timer>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
      <Triggers>
            <asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick" />
      </Triggers>
      <ContentTemplate>
            <asp:Label ID="Label1" runat="server"></asp:Label>
</asp:UpdatePanel>

c# code below..

protected void Timer1_Tick(object sender, EventArgs e)
{
     Label1.Text = DateTime.Now.ToShortTimeString().ToString();
}

Above code will fetch current time for regular interval of 1 second. You place your code inside update panel and give time as much you wanted to refresh the content..